Synchronization Harmonizer for Network Domain Selection

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Solution Overview

Problem

Communication networks, particularly those using LTE-based radio access technologies, face challenges in achieving accurate time and phase synchronization due to variance in send, access, and receive times, as well as unpredictable delays caused by different physical transport technologies, which affects the performance of synchronization protocols.

Innovation Solution

A harmonizer is introduced to determine and select appropriate synchronization references and paths for access nodes by determining backhaul domains and interconnected transport links, allowing for the configuration of differentiated synchronization services without impacting existing hardware or control domains, thereby minimizing phase deviation between radio base stations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If PTP messages are distributed from a centralized Grandmaster entity through multiple hops, then network infrastructure flexibility is improved, but synchronization accuracy deteriorates due to multiple hops and unpredictable delays

Engineering Contradiction:
Improvenetwork infrastructure flexibilityVSAvoidsynchronization accuracy
Core Design Contradiction:
Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The network is segmented into multiple synchronization domains, each with its own boundary clock that acts as a local synchronization source. This divides the large centralized network into smaller manageable segments, reducing the number of hops PTP messages must traverse within each segment while maintaining overall network flexibility through the hierarchical structure of multiple domains.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Boundary clocks serve as intermediary devices between the Grandmaster entity and ordinary clock nodes. These boundary clocks receive synchronization information from the Grandmaster and redistribute it within their local domains, acting as mediators that reduce the propagation path length and improve synchronization accuracy without compromising network infrastructure flexibility.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Adaptability or versatility

If physical transport technologies (microwave, fibre, copper wire) are used to support broad network topologies, then network coverage and adaptability are improved, but synchronization reliability deteriorates due to unpredictable delay variation

Engineering Contradiction:
Improvenetwork coverageVSAvoidsynchronization reliability
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

Different synchronization quality levels are applied to different physical transport media. Boundary clocks identify the type of physical transport being used and apply appropriate synchronization processing and timestamp compensation specific to that medium's characteristics, ensuring reliable synchronization regardless of whether microwave, fibre, or copper wire is used.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The system dynamically adjusts synchronization parameters based on the detected physical transport technology. Different timestamp compensation values, delay measurement intervals, and synchronization algorithm parameters are applied according to the specific characteristics of each transport medium, maintaining synchronization reliability across diverse physical infrastructure.

Inventive Principle:
Principle #35Parameter changes

3Adaptability or versatility

If multiple synchronisation references are available for access nodes, then synchronization service differentiation is improved, but system complexity increases due to the need to determine and select appropriate references

Engineering Contradiction:
Improvesynchronization service differentiationVSAvoidsystem complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The harmonizer performs preliminary analysis and determination of appropriate synchronization references before actual synchronization service deployment. It pre-configures the network with information about available synchronization sources and their characteristics, so that when access nodes need synchronization services, the selection process is simplified based on pre-computed optimal configurations.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The harmonizer enables access nodes to autonomously select appropriate synchronization references based on pre-provided configuration information and current network conditions. Each access node can independently determine the best synchronization source from available options without requiring complex centralized coordination for each selection decision.

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP3320727B1Method and apparatus for determining synchronisation references
Publication Date: 2021.01.06 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
  • EP3320727B1 patent drawingFigure 1
  • EP3320727B1 patent drawingFigure 2
  • EP3320727B1 patent drawingFigure 3

AI summary

A backhaul domain of the communication network is determined 400, and a request for a synchronisation reference is received 402 from the first access node, the request comprising, ID:s of the first and second access nodes. For each one of the first and second access nodes, a first and a second combination are determined 404 of a first and a second respective synchronisation reference and related synchronisation paths extending between synchronisation reference nodes of the synchronisation references and the access nodes. For each one of the first and second access nodes, the first or the second combination of synchronisation reference and related synchronisation path is selected 406 based on synchronisation requirements for the first and second access nodes, and the first path or the second path is requested to be set-up 408 according to the selected 406 combination. By providing functionality which works on the top of existing control of radio and transport domains, appropriate synchronisation references may be determined with a limited amount of information exchanged between the respective domains.